Posts Tagged ‘acl ios’

Today here in this article we learn how to configure Firewall on cisco routers.As we know cisco uses IOS.For security purpose it’s become essential to learn  the concept of Firewall and to know how to  configure Firewall on Routers.The IOS Firewall is a stateful firewall that inspects TCP and UDP packets at the application layer of the OSI model. Not only that but it also used to  watch the outgoing requests (usually to the Internet) and opens reciprocal, inbound ports for the return traffic.Many companies uses different types of Firewalls,some at OS level some are hardware based.Here we are talking about CISCO IOS Firewall which  is an inbuilt FIREWALL  inside the cisco Router.The most important thing to be kept in mind about IOS FIREWALL is that the IOS Firewall maintains the state of each of the TCP connections; it allows return traffic back if it allowed it out and if it matches the state information stored for that TCP packet.

(more…)